1. Field of the Invention
The present invention relates to a focal plane shutter, a photographing apparatus including the same, and a photographing method for the photographing apparatus, and more particularly, to a focal plane shutter, which is easily manufactured and controlled because of its simple mechanical structure and can offer a live view function, a photographing apparatus including the focal plane shutter, and a photographing method for the photographing apparatus.
2. Description of the Related Art
It is now easier for novice photographers to take photographs like professional photographers due to the popularization of digital single lens reflex (DSLR) cameras, which are single lens reflex cameras that take digital photographs.
Here, “single lens reflex” refers to a method of transmitting light of an object to a viewfinder through a single lens or transmitting the light to a sensor that can record an image. Frequently used consumer-grade digital cameras are twin lens digital cameras. Therefore, an image that can be seen through a viewfinder of a consumer-grade digital camera is different from an image photographed with the generally used digital camera.
In a conventional single lens reflex camera, a mirror is formed on an optical axis of a lens so as to be rotatable within a predetermined angular range about the optical axis. Under normal conditions, object light obtained by the lens is reflected by the mirror, and an image of an object is formed on a focus plate. Thus, a photographer can view the image of the object by using a pentaprism and a viewfinder. At this time, when a shutter-release signal is input, the mirror rotates around a shaft within the predetermined angular range and ascends to retreat from the optical axis of the lens. When a shutter is opened under the control of a shutter driving circuit, the image of the object is formed on an image pickup device.
In such a conventional single lens reflex camera as described above, a shutter moving to allow light to pass for only a predetermined period of time is disposed in front of an image pickup device. This shutter is called a focal plane shutter because it is located in front of an image pickup device.
However, a conventional focal plane shutter is connected to a quick return system of a single lens reflex camera and thus has a complicated mechanical structure. As a result, it is not easy to manufacture and control such a conventional focal plane shutter.
Since a lens for use in a digital single lens reflex camera can be interchanged with standard lenses or lenses designed exclusively for digital cameras, suitable lenses can be selectively used according to the preference or objective of a user. Also, since digital single lens reflex cameras generally have an image pickup device much bigger than that of other conventional digital cameras, the generation of noise can be prevented under low illumination conditions and a more precise image can be captured.
However, since the mirror is located to cover the image pickup device, an image cannot be seen on a liquid crystal display (LCD) during shooting, that is, a live view (also known as a preview) function is not offered, and the LCD of the single lens reflect camera can only be used to perform menu manipulation and an image review following image capture. That is, since an image should be seen through an optical viewfinder, the ability to view the image to be formed is limited when taking a picture at certain postures/positions, such as, at a low angle and a high angle, and thus this decreases the ability and convenience of photography using such a camera. Also, when a subject which is sensitive to action, such as a bird, is to be photographed using a single lens reflect camera, the user must view the subject for a long time. However, in this situation, use of the single lens reflect camera is inconvenient because the user must view the subject through the optical viewfinder and because the single lens reflect camera is too heavy to hold for a long time in the same position.